Cloud computing has gained substantial momentum over the past few years, fueling technological innovation and creating considerable business impact. Public, private or hybrid cloud infrastructure shortens users' time to market (new hosting infrastructure is only a few mouse-clicks away), and claims to reduce their total cost of ownership by shifting the cost structure from higher capital expenditure to lower operating expenditure.
One of the key advantages of cloud computing is the ability to build dynamically scaling systems. Virtualization technologies (including XEN, KVM, VMware, Solaris and Linux Containers) facilitate clustered computing services to acquire and release resources automatically. This enables dynamically right-sizing the amount of resources that are actually needed, instead of statically over-dimensioning the capacity of such clustered services. Some key advantages emerging from dynamic right-sizing include (1) the ability to reduce the services' operational cost and (2) the ability to gracefully handle unanticipated load surges without introducing opportunity loss by compromising the service's SLA.
Although most existing dynamic scaling solutions have been targeting web and enterprise applications, also clustered and “cloudified” telecommunication services (such as SIP farms hosted by public or private clouds) can significantly benefit from the advantages of dynamic scaling. To guarantee carrier grade service execution, for instance, telecommunication operators typically over-dimension the employed resources—at the expense of reducing their resource utilization ratio, and thus raising their operational cost. This cost increases even more when the operator needs to provision sufficient resources to handle sporadic unanticipated load surges (caused by events with a significant social impact) or anticipated load spikes (e.g. caused by New Year's Eve texting).